The present invention relates to lumber finishing apparatus, and more particularly to a novel belt sanding apparatus for sizing and finishing batches of lumber.
In the surface finishing of rough-sawn lumber, it is known to convey the lumber through rotating knife planer heads for finishing the lumber. The knife planer heads may be positioned on opposite sides of a path of conveyance for finishing opposite faces of the lumber. However, construction of an apparatus for finishing lumber using knife planer heads is expensive. Additionally, maintenance of individual knife blades is time consuming and expensive because the blades must be periodically removed, sharpened and replaced.
While it has been proposed to finish lumber using abrasive belt sanders rotatably mounted by means of a driven contact drum or roll, the use of such sanders has been directed to finishing only after knife planer heads have dimensionally sized the lumber to a predetermined thickness. Additionally, the abrasive belt of the sander includes a splice which is raised somewhat above the surface of the belt thereby causing a splice mark on the lumber as it is sanded. As lumber is conveyed through a belt sander, the splice marks produce a so-called "ripple" which is undesired in a finished product. Additionally, the belt will produce undesirable contact roll revolution marks.
Accordingly, it is a general object of the present invention to provide an apparatus for sizing and finishing batches of lumber which includes a sizing station and a finishing station. More specifically, the sizing station includes a pair of opposed, power-driven belt sanders for receiving and sanding opposite surfaces of lumber so that the lumber exits from the sizing station with a predetermined thickness.
Another object of the present invention is to construct the finishing station with staggered belt sanders. This is known as a "staggered head" sander and refers to positioning of belt sanders on opposite sides of the path of lumber conveyance wherein one belt sander is positioned downstream from the other.
Still another object of the present invention is to construct the sizing station with additional opposed belt sanders for receiving batches of lumber after they have been conveyed through the first pair of opposed belt sanders. Thus, it is possible to eliminate knife planer heads for dimensionally sizing the thickness of batches of lumber by providing two pairs of opposed belt sanders which successively abrade or sand the lumber to a predetermined thickness.
These and additional objects and advantages of the present invention will be more particularly appreciated after a consideration of the drawings and the detailed description of the preferred embodiment.